Chabahar lies in Sistan-Baluchistan near the border with Pakistan. The province has a Sunni Muslim ethnic Baluchi minority that straddles the border with Pakistan, where Baluchi separatists and jihadis are active.

"Iran will bring terrorists and their masters to justice," he wrote on Twitter.

Uptick in terror attacks

Terror attacks in Shiite Iran are rare, but militants have stepped up action in recent months. In September, gunmen dressed as soldiers attacked a military parade in Ahvaz, killing and injuring dozens. Arab separatists and the "Islamic State" (IS) issued competing claims for the attack, which prompted Iran to launch ballistic missiles at IS targets in Syria.